8 ohm load to 4 ohm driver.

mhmacw

what really happens when you deliver an 8 ohm signal to a 4 ohm driver?

concealer404

Nothing, because that's not how that works.

steveinaz

"8 ohms" refers to how much resistance is present, it's not a signal. Are you asking what happens when you drive a 4 ohm speaker with an 8 ohm specified amp?

mhmacw

well i have a low impedance switch on my amp and i know the voice coils are 4 ohm. i wonder what happens when i run 4 ohm coils on "high "impedance setting or 8 ohm. ive run other speakers that are rated 8 ohm on the low setting but they werent dual coils. i just didnt want to fry anything. it seems to me the sound is more defined on high impedance.

mhmacw

concealer404 wrote: »

Nothing, because that's not how that works.

not how what works? ive gone lower on speakers but not higher. lol what going to smoke first?

steveinaz

Set your amp switch to the "nominal" impedance of your speakers. Look at your speaks spec sheets to get the nominal (aka "average") impedance. When in doubt, go with the lower 4 ohm setting (amp) to protect the amp against too much current draw, in case your speakers happen to be 4 ohm.

mhmacw

steveinaz wrote: »

Set your amp switch to the "nominal" impedance of your speakers. Look at your speaks spec sheets to get the nominal (aka "average") impedance.

it is dual voice coil so it could be 2,4 or 8. right now i have a channel to each coil at low impedance(4 ohm). but it tightens up and sounds much more crisp when i switch to 8 ohm. is it going to explode?lol should i order a new one right now?

concealer404

mhmacw wrote: »

well i have a low impedance switch on my amp and i know the voice coils are 4 ohm. i wonder what happens when i run 4 ohm coils on "high "impedance setting or 8 ohm. ive run other speakers that are rated 8 ohm on the low setting but they werent dual coils. i just didnt want to fry anything. it seems to me the sound is more defined on high impedance.

Either way, your amp will attempt to drive a 4ohm load, because that's what you're presenting to it. You don't have control over that as long as you run that driver.

It's up to you to decide/find out if your amp is up to the task.

steveinaz

mhmacw wrote: »

well i have a low impedance switch on my amp and i know the voice coils are 4 ohm. i wonder what happens when i run 4 ohm coils on "high "impedance setting or 8 ohm. ive run other speakers that are rated 8 ohm on the low setting but they werent dual coils. i just didnt want to fry anything. it seems to me the sound is more defined on high impedance.

An amp set to drive 8 ohm speakers may overheat/shut down trying to drive a 4 ohm load, due to too much current.

steveinaz

mhmacw wrote: »

it is dual voice coil so it could be 2,4 or 8. right now i have a channel to each coil at low impedance(4 ohm). but it tightens up and sounds much more crisp when i switch to 8 ohm. is it going to explode?lol should i order a new one right now?

What speaker are you driving?

mhmacw

steveinaz wrote: »

What speaker are you driving?

its my subwoofer. im waiting on my plate amp so im using another old receiver for the next week or so

mhmacw

concealer404 wrote: »

Either way, your amp will attempt to drive a 4ohm load, because that's what you're presenting to it. You don't have control over that as long as you run that driver.

It's up to you to decide/find out if your amp is up to the task.

so should it be switched to 4 ohm(i checked the manual its 4 and 8 ohm) or will it do it anyway?

concealer404

mhmacw wrote: »

so should it be switched to 4 ohm(i checked the manual its 4 and 8 ohm) or will it do it anyway?

It'll do it anyways. It doesn't matter what you set the reciever to, it'll still see the same load from the driver, so it'll do whatever is necessary by the driver.

Switching to 4ohm probably just trips some kind of limiter to prevent overheating. It shouldn't change how the power is sent or created.

steveinaz

To be on the safe side, keep it at 4ohms--unless you can find out definitively what the nominal impedance is of the sub.

Here's the deal; less impedance requires a more robust amplifier (I know, it seems counter-intuitive). When resistance (impedance) drops, current rises---too much current and the amplifier section of the receiver will overheat/shutdown. An 8 ohm load is easier to drive because there is not as much current demand on the amplifier section. This is why your better amplifiers are "high current" designs that will safely drive lower impedances---giving you more flexibility in speaker choice.

mhmacw

they are 4 ohm coils i know that much lol...its rocking the house with 100(supposed) watts im a little scared to see what itll do to the windows with the 500 watt 8 ohm amp. it sounds good too i just didnt want to break it befoer its broke in thats all.

steveinaz

How are you running it without the plate amp? Tell me you're not connected directly to the bass driver, right? Although you'll probably smoke the receiver long before the driver....LOL

mhmacw

steveinaz wrote: »

How are you running it without the plate amp? Tell me you're not connected directly to the bass driver, right?

LOL I wondered how long that would take to get this question haha. no im not connected un filtered to the source. i went sub out from my main receiver to a y splitter to the phono in on the old receiver. they both have a 47K ohm impedance rating.

steveinaz

WHAT? Unhook that crap man. Sub-out to phono-in? Are you serious? Why would you run from one receiver to another using the sub-out and phono in? What's that suppose to accomplish---other than god-awful sound?

Damn Funkenbush, wait for the plate amp to come.

mhmacw

steveinaz wrote: »

WHAT? Unhook that crap man. Sub-out to phono-in? Are you serious?

yea why not?

steveinaz

NO...more like "WHY?"

You have a sub output (line level signal) going into a phono input (preamplified, NOT a line level input) that is not designed in any way, shape or form to handle a sub signal.

It's like connecting my motorcycle alternator to my cars AC and asking why my left speaker doesn't work...ROTFLMAO!!!

The really funny things is....you're concerned about which position to put the receivers impedance matching circuit switch to, you're killin me man. That's like buying an airplane because you like free peanuts.

mhmacw

steveinaz wrote: »

WHAT? Unhook that crap man. Sub-out to phono-in? Are you serious? Why would you run from one receiver to another using the sub-out and phono in? What's that suppose to accomplish---other than god-awful sound?

Damn Funkenbush, wait for the plate amp to come.

whats the problem? its not like im blasting any thing and it gives me a chance to tune the box ports. sure the headroom is like crawling under a car but. just turn it all down and at least you can tune **** at least the mechanical tuning part. funkenbush ...that s funny. the impedancese are the same .sooo electronicaly it isnt goin to hurt anything. just the presence of that sub is plenty believe me. yea its not "preffered" but hell its just a dx -940 any way if it blows it blows. however.... "polk guru" i will go unplug it and wait for the amp....&#$*!$&^ i hate mentors sometimes lol

steveinaz

You are a crazy man, and I dig that about you baby! LOL!!! Classic!

mhmacw

steveinaz wrote: »

You are a crazy man, and I dig that about you baby! LOL!!! Classic!

if i keep it between the fences do i really have to unplug it?

dudeinaroom

Take it off the phono in, and run it into a tape,cd, or an aux in. dx- 940? Or is it a SA-DX940?

TNRabbit

Do anything you want; it's obvious you're going to anyway. Just don't come crying to us when you destroy your system~

mhmacw

dudeinaroom wrote: »

Take it off the phono in, and run it into a tape,cd, or an aux in. dx- 940? Or is it a SA-DX940?

i thought of that but the impednace is wrong. 22k for the cd and 47k for the phono. its an sasdx940. an old technics piece of **** that was lying around so ...se la vie if it does go.

mhmacw

TNRabbit wrote: »

Do anything you want; it's obvious you're going to anyway. Just don't come crying to us when you destroy your system~

lol cry? i wouldnt hold my breath if i were you! go buy another...or 10 more if i so desire... likely. as for doing anything i want TCH!!! why the hell do you think i asked? it is unpluggeed , i am waiting for the plate amp and i did take steves advice so i guess you missed that one too eh?

mhmacw

mhmacw wrote: »

if i keep it between the fences do i really have to unplug it?

guess i should have put one of those sarcastic faces behind this post so those with out a sence of humor wouldnt have been confused

unc2701

1) The phono input expects no more than about 10mv; the sub output can put out up to around 2000mv
2) There's a reverse RIAA on the phono input. This boosts the bass and drops the treble. If what you're listening to has any subsonics it's possible that it'll melt your voice coil.

So, move to a CD or tape input, set the switch to 4ohm and sit tight until the plate amp arrives.

mhmacw

unc2701 wrote: »

1) The phono input expects no more than about 10mv; the sub output can put out up to around 2000mv
2) There's a reverse RIAA on the phono input. This boosts the bass and drops the treble. If what you're listening to has any subsonics it's possible that it'll melt your voice coil.

So, move to a CD or tape input, set the switch to 4ohm and sit tight until the plate amp arrives.

hey thanks man. the specs said 37 mv for the sub out so i figured it wasnt too bad. i took it down so no worries but thanks for the info.

unc2701

OK, the input sensitivity on your phono input is 0.4mv, so you will overload it- what's your AVR for the sub out? 37mv seems like a weird spec for that.